1. Field of the Invention
The present invention relates to a color filter suitable for a color liquid crystal display which can be used in a color television, a personal computer or the like, a method for manufacturing the color filter, and a liquid crystal panel equipped with the color filter. More specifically, it relates to a color filter for liquid crystal displays manufactured by the utilization of an ink jet recording technique, a method for manufacturing the color filter, and a liquid crystal panel equipped with the color filter.
2. Related Background Art
In recent years, there has been a tendency that the demand of liquid crystal displays, particularly color liquid crystal displays increases with the development of personal computers, particularly portable personal computers. However, for the further spread of the liquid crystal displays, it is necessary to lower their costs, and particularly with regard to the color filter which largely occupies the cost of each display, request for its cost reduction increases. In order to meet the required characteristics of the color filter and to satisfy the above-mentioned demand, various attempts have been heretofore made, but any method which can meet all of the required characteristics has not been established so far. Some methods for manufacturing the color filter will be described below.
A first method which has most often been used is a dyeing method. This dyeing method comprises coating a glass substrate with an aqueous polymer material which is a material to be dyed, patterning the material into a desired shape by a photolithography process, and then immersing the thus obtained pattern in a dyeing bath to obtain a colored pattern. This operation is repeated three times to form the colored layers of Red (R), Green (G) and Blue (B).
Japanese Patent Application Laid-Open No. 5-288913 has described another example of this dyeing method which comprises forming a photosensitive layer, exposing it to light through a pattern, dyeing unexposed portions, and then repeating this process to manufacture a color filter having three colors of R, G and B.
A second method is a pigment dispersion method, which is now being replaced with the above-mentioned dyeing method. This pigment dispersion method comprises first forming, on a substrate, a photosensitive resin layer in which a pigment is dispersed, and then patterning the resin layer to obtain a single-colored pattern. Next, this process is repeated three times to form colored layers having three colors of R, G and B.
A third method is an electrodeposition method. This method comprises first patterning transparent electrodes on a substrate, and then immersing it in an electrodeposition coating solution containing a pigment, a resin, an electrolyte and the like to electrodeposit a first color. This process is repeated three times to form colored layers of R, G and B, and in the last step, these layers are calcined.
A fourth method is a printing method. This method comprises dispersing a pigment in a thermosetting resin, repeating a printing operation three times to coat with the colors of R, G and B, and then thermosetting the colored resin layers to form colored layers. In each of these methods, a protective layer is usually formed on the colored layers.
A point which is common to these methods is that a similar process is required to be repeated three times to give the three colors of R, G and B, which increases the cost. In addition, these methods having many steps lead to deterioration of a yield. Moreover, in the electrodeposition method, the formable patterns are limited, and so it is difficult to apply this method to TFT by an existent technique. The printing method has a drawback that resolution properties and smoothing properties are poor, and so it is not suitable for the formation of a pattern having a fine pitch.
In order to overcome these drawbacks, techniques for manufacturing a color filter by the use of an ink jet system have been developed, and these techniques have been described in Japanese Patent Application Laid-Open Nos. 59-75205, 63-235901 and 1-217320. However, a sufficiently satisfactory method has not been obtained yet.